Each country adopts a set of patron saints, members of the heavenly court who are special intercessors for all those within a particular country’s borders. It took the bishops of the newly created United States of America 70 years to appoint the Blessed Virgin Mary as patroness of their country. In doing so, they invoked Mary under her title of Our Lady of the Immaculate Conception.
It was a choice met with unanimous support, one that was based on many different factors.
The decision was reached on May 13, 1846, during the Sixth Provincial Council of Baltimore.
With enthusiastic acclaim and with unanimous approval and consent, the Fathers [of the Council] have chosen the Blessed Virgin Mary, conceived without sin, as the Patroness of the United States of America.